Illuminating system.



H. SIBDENTOPF.

ILLUMINATING SYSTEM.

APPLICATION FILED PB. 22.1909.

Patented Aug. 3, 1909 /mmm is employed,

UNITED STATES PATENT OFFICE.

HENRY SIEDENTOPI", 0] JENA, GERMANY, ASSIGNOR T0 FIRM (H Altl, ZEISS, 01 JENA, GERMANY.

ILLUMINATING SYSTEM.

Specification of Letters Patent.

Patented Aug. 3, 1909.

To all whom it may concern:

Be it known that I, HENRY Srnnnnrorr, a citizen of the German Empire, and residin at Carl-Zeiss strassc, Jena, m the Grand Duchy of Saxc-Veimar, Germany, have in vented a new and useful Illuminating System, of which the following is a specification. r

The invention relates to illun'iinatin systems intended for receiving the rays of light on one side as a parallel or weakly convergent or divergent pencil and to transmit them to the other side as a powerfully convergent encil. This roblem has hitherto been so ved in a dioptrrcal wa but in not quite a satisfactory manner, ecause a multi-eomposite system is requisite to obtain a tolerable correction.

The present improvement consists in only a core of the pencil obtainin the powerful convergence b refraction, w ereas the remainin annu ar art obtains it by reflection. bus the i1 uminating system can be com osed of two different, but comparative y simple parts, a central refracting one and a 1peripheral reflecting one.

In t e reflecting s stem part simple reflection, in fact any 0 d number of successive reflections should be particularly avoided for the following reasons. Firstly, the adjustm'ent of the system arts relatively to each other would have to' e altered in order to maintain the union of the rays, each time a pencil of rayxs of a slightlydifl'erent aperture ecause in that case the oint of convergence of the rays reflected an odd number of times moves in an opposite direction as the goint of convergence of the refracted re s. v econdtly in the annular cone of rays be ind the re ecting system part, the order of the rays between the concave and the convex cone surface would be reversed to that in the ring of rays in front of this system part. Two disadvantages would consequentarise. On the one hand, behind the system,

t e intensity of illumination from the axis to the convex surface of the entire cone would no longer show a continuous course, but would increase in the transition from the core cone of the refracted re s to the annular cone of the reflected rays wit a discontinuit On the other hand an iris diaphragm, whic with regard to the lpowerful convergence of the pencil leavmg t e system can practically only laced in front of the system, would indeed, when commuted, begin by stoppin down the annular cone, but in a reverse direction, namely, from inside to outside.

The advantage of an even number of reflections would be realized practically in hardly any other manner than by double reflection. The reflecting surfaces are suitably arranged iu Stophensons microscope condenser for dark ground illumination by giving a glass body producing the first reflection a convex, silvered, annular back surface, but shaping its front surface so as to effect the second reflection with the peri heral art of this surface.

S ould t 1c refracting system part be provided with a separate front lens, this latter can be mounted without stopping out an parts of the ring of the rays to be reflected, if it be constructed of two parts and one of these enetrates on all sides outwardly through the ring of rays In the drawing a portstructional form of the new catadio tric illuminating system is shown in an axia section.

Through the full 0 ened iris diaphragm a there enters a cy in er of re s parallel to the axis, of which 1, 1, as sur ace rays, belong to the core cylinder of the rays to be refracted, 2, 2 and 3, 3, however, as rays of the concave and the convex surfaces, to the annular cylinder of the rays to be reflected.

The core cylinder of rays is refracted by the front lens, which consists of a piano-convex part b and a piano-parallel part c cemented risk 0, rejecting beyond the lens b, and into the dis 2 cemented with the lens d. In this disk it is reflected by the silvered' art e". of the back surface, fOlHitdflS a zone 0 a parabolold, and thereupon undergoes a second, total reflection on the front surface of the disk e. As shown the core cone is supplemented by the annular cone into an uninterrupted total cone. This illuminating cone from the disk e asses without refraction through a spherica surface concentric to its apex, the cavity of which surface amplifies at the same time the space for the obifict to be illuminated. Should a more big y refractive medium than air be intercalated between the disk e and theobject, the plane back surface of the disk a does not require to be made discontinuous 1w a concave exit surface. As regards the retracting systemv part, it should iurtlmrniore he pointed out, that even without increasing the number of gluss bodies its spherical corroctioncan he nnprovod and it chromatic correction obmined. For this purpose, besides a suitable selection of the kinds of glass, theeonstruw tion of one of the two cemented surfaces, perhaps also of the core part of the exit our ace of c, with finite radius, further a reduction in the radius of curvature of the core part of the exit surface of r, and even a deformation of one or the other spherical surface may prove serviceable.

By means of the iris diaphragm a it is possible to continuously cut down the annular cone from outside inward and further in the same direction the core cone until each is extin uished claim: I

1. An illuminating system constructed to cause a pencil which enters on the one side with parallel rays to emerge on the other side with powerfully convergent rays and cornprising a central refraoting part and a pcripheral reflecting part, the letter comprising an even number of reflecting surfaces.

2. An illuminatin system constructed to cause a pencil whici enters on the one side with parallel rays to emerge on the other side with powerfully mnvergent rays and com prising a, control roll-acting port and a poripheral reflecting port, the latter being a less bod which comprises two annular reeeting surfaces, one a buck surface and the other a front surface, and the back surface being convex and silvered.

3. A11 illuminating system constructed to cause a pencil which enters on the one side with parallel rays to emerge on'the other side with powerfully convergent rays and comprising a central rofracting part and a poripheral reflecting part, the refracting part including a separate front double lens one of the components of which extends th the annular s ace of the peripheral rays to be reflected, t 1e reflecting part being a, glass body which comprises two annular reflecting surfaces, one a back surface and the other a front surface, and the back surface being convex and silvered.

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